I'm editting this post because maybe I was clear enough. If you run high octane gas and dont have the compression to burn it, it simply wont burn and you'll run rich. If you decrease the amount of gas, even though you have less to burn, it doesnt mean you can now burn it because there's less. If you dont have the compression you simply wont burn it. If you dont have enough gas you might just not get the bike to even run.